A novel inverse relationship between metformin-triggered AMPK-SIRT1 signaling and p53 protein abundance in high glucose-exposed HepG2 cells

AMP-activated protein kinase (AMPK) and the NAD+-dependent histone/protein deacetylase sirtuin 1 (SIRT1) are metabolic sensors that can increase each other's activity. They are also both activated by the antidiabetic drug metformin and downregulated in the liver under conditions of nutrient excess (e.g., hyperglycemia, high-fat diet, obesity). In these situations, the abundance of the tumor suppressor p53 is increased; however, the relevance of this to the changes in AMPK and SIRT1 is not known. In the present study we investigated this question in HepG2 cells under high glucose conditions. Metformin induced activation of AMPK and SIRT1 and decreased p53 protein abundance. It also decreased triglyceride accumulation and cytosolic oxidative stress (a trigger for p53 accumulation) and increased the deacetylation of p53 at a SIRT1-targeted site. The decrease in p53 abundance caused by metformin was abolished by inhibition of murine double minute 2 (MDM2), a ubiquitin ligase that mediates p53 degradation, as well as by overexpression of a dominant-negative AMPK or a shRNA-mediated knockdown of SIRT1. In addition, overexpression of p53 decreased SIRT1 gene expression and protein abundance, as well as AMPK activity in metformin-treated cells. It also diminished the triglyceride-lowering action of metformin, an effect that was rescued by incubation with the SIRT1 activator SRT2183. Collectively, these findings suggest the existence of a novel reciprocal interaction between AMPK/SIRT1 and p53 that may have implications for the pathogenesis and treatment of metabolic diseases.

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Metformin, metabolic stress, and mitochondria. Focus on “A novel inverse relationship between metformin-triggered AMPK-SIRT1 signaling and p53 protein abundance in high glucose-exposed HepG2 cells”

AJP Cell Physiology ◽

10.1152/ajpcell.00090.2012 ◽

2012 ◽

Vol 303 (1) ◽

pp. C1-C3 ◽

Cited By ~ 12

Author(s):

Mary C. Sugden ◽

Mark J. Holness

Keyword(s):

High Glucose ◽

Hepg2 Cells ◽

Inverse Relationship ◽

P53 Protein ◽

Metabolic Stress ◽

Protein Abundance

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Elevated Glucose and Insulin Levels Decrease DHA Transfer across Human Trophoblasts via SIRT1-Dependent Mechanism

Nutrients ◽

10.3390/nu12051271 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1271

Author(s):

Jay S. Mishra ◽

Hanjie Zhao ◽

Sari Hattis ◽

Sathish Kumar

Keyword(s):

Fatty Acid ◽

High Glucose ◽

Molecular Mechanisms ◽

Sirtuin 1 ◽

Dependent Manner ◽

Sirt1 Expression ◽

Insulin Levels ◽

Triglyceride Accumulation ◽

Elevated Glucose ◽

Fatty Acid Transporter

Gestational diabetes mellitus (GDM) results in reduced docosahexaenoic acid (DHA) transfer to the fetus, likely due to placental dysfunction. Sirtuin-1 (SIRT1) is a nutrient sensor and regulator of lipid metabolism. This study investigated whether the high glucose and insulin condition of GDM regulates DHA transfer and expression of fatty acid transporters and if this effect is related to SIRT1 expression and function. Syncytialized primary human trophoblasts were treated with and without glucose (25 mmol/L) and insulin (10−7 mol/L) for 72 h to mimic the insulin-resistance conditions of GDM pregnancies. In control conditions, DHA transfer across trophoblasts increased in a time- and dose-dependent manner. Exposure to GDM conditions significantly decreased DHA transfer, but increased triglyceride accumulation and fatty acid transporter expression (CD36, FABP3, and FABP4). GDM conditions significantly suppressed SIRT1 mRNA and protein expression. The SIRT1 inhibitor decreased DHA transfer across control trophoblasts, and recombinant SIRT1 and SIRT1 activators restored the decreased DHA transport induced by GDM conditions. The results demonstrate a novel role of SIRT1 in the regulation of DHA transfer across trophoblasts. The suppressed SIRT1 expression and the resultant decrease in placental DHA transfer caused by high glucose and insulin levels suggest new insights of molecular mechanisms linking GDM to fetal DHA deficiency.

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Nobiletin Inhibits Hepatic Lipogenesis via Activation of AMP-Activated Protein Kinase

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2018/7420265 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 13

Author(s):

Taewon Yuk ◽

Younghwa Kim ◽

Jinwoo Yang ◽

Jeehye Sung ◽

Heon Sang Jeong ◽

...

Keyword(s):

Protein Kinase ◽

High Glucose ◽

Lipid Accumulation ◽

Hepg2 Cells ◽

Fatty Acid Synthase ◽

Regulatory Element ◽

Hepatic Lipogenesis ◽

Nonalcoholic Fatty Liver ◽

Compound C ◽

Amp Activated Protein Kinase

We aimed to investigate the effects of nobiletin on hepatic lipogenesis in high glucose-induced lipid accumulation in HepG2 cells. Nobiletin, a citrus polymethoxyflavonoid with six methoxy groups, is present abundantly in the peels of citrus fruits. HepG2 cells were incubated in Dulbecco’s modified Eagle’s medium containing high glucose (25 mM) and subsequently treated with nobiletin at different concentrations (5, 25, and 50 μM). Results showed that nobiletin markedly inhibited high glucose-induced hepatic lipid accumulation in HepG2 cells. In addition, it reduced the protein expression of lipogenic factors, including sterol regulatory element-binding protein 1c (SREBP-1c) and fatty acid synthase (FAS). Nobiletin significantly increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase. Pretreatment with compound C, an AMPK inhibitor, abolished the inhibitory effects of nobiletin on SREBP-1c and FAS expression. These results suggested that nobiletin might attenuate high glucose-induced lipid accumulation in HepG2 hepatocytes via modulation of AMPK signaling pathway. Therefore, nobiletin might be useful for the prevention and treatment of nonalcoholic fatty liver diseases.

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Saponins from Platycodon grandiflorum inhibit hepatic lipogenesis through induction of SIRT1 and activation of AMP-activated protein kinase in high-glucose-induced HepG2 cells

Food Chemistry ◽

10.1016/j.foodchem.2013.02.041 ◽

2013 ◽

Vol 140 (1-2) ◽

pp. 115-123 ◽

Cited By ~ 20

Author(s):

Yong Pil Hwang ◽

Jae Ho Choi ◽

Hyung Gyun Kim ◽

Hyun-Sun Lee ◽

Young Chul Chung ◽

...

Keyword(s):

Protein Kinase ◽

High Glucose ◽

Hepg2 Cells ◽

Hepatic Lipogenesis ◽

Platycodon Grandiflorum ◽

Amp Activated Protein Kinase

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Hydroxytyrosol improves mitochondrial function and reduces oxidative stress in the brain of db/db mice: role of AMP-activated protein kinase activation

British Journal Of Nutrition ◽

10.1017/s0007114515000884 ◽

2015 ◽

Vol 113 (11) ◽

pp. 1667-1676 ◽

Cited By ~ 58

Author(s):

Adi Zheng ◽

Hao Li ◽

Jie Xu ◽

Ke Cao ◽

Hua Li ◽

...

Keyword(s):

Oxidative Stress ◽

Protein Kinase ◽

Mitochondrial Function ◽

High Glucose ◽

Sirtuin 1 ◽

Related Factor ◽

Expression Levels ◽

Ampk Pathway ◽

Amp Activated Protein Kinase ◽

The Brain

Hydroxytyrosol (HT) is a major polyphenolic compound found in olive oil with reported anti-cancer and anti-inflammatory activities. However, the neuroprotective effect of HT on type 2 diabetes remains unknown. In the present study, db/db mice and SH-SY-5Y neuroblastoma cells were used to evaluate the neuroprotective effects of HT. After 8 weeks of HT administration at doses of 10 and 50 mg/kg, expression levels of the mitochondrial respiratory chain complexes I/II/IV and the activity of complex I were significantly elevated in the brain of db/db mice. Likewise, targets of the antioxidative transcription factor nuclear factor erythroid 2 related factor 2 including p62 (sequestosome-1), haeme oxygenase 1 (HO-1), and superoxide dismutases 1 and 2 increased, and protein oxidation significantly decreased. HT treatment was also found to activate AMP-activated protein kinase (AMPK), sirtuin 1 and PPARγ coactivator-1α, which constitute an energy-sensing protein network known to regulate mitochondrial function and oxidative stress responses. Meanwhile, neuronal survival indicated by neuron marker expression levels including activity-regulated cytoskeleton-associated protein, N-methyl-d-aspartate receptor and nerve growth factor was significantly improved by HT administration. Additionally, in a high glucose-induced neuronal cell damage model, HT effectively increased mitochondrial complex IV and HO-1 expression through activating AMPK pathway, followed by the prevention of high glucose-induced production of reactive oxygen species and declines of cell viability and VO2 capacity. Our observations suggest that HT improves mitochondrial function and reduces oxidative stress potentially through activation of the AMPK pathway in the brain of db/db mice.

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Protective Effect of Astragalus Polysaccharide Against High glucose‐induced Endoplasmic Reticulum Stress by Activation of AMP‐activated Protein Kinase in Human HepG2 Cells

The FASEB Journal ◽

10.1096/fasebj.23.1_supplement.578.10 ◽

2009 ◽

Vol 23 (S1) ◽

Author(s):

Jian Liu ◽

Huan Jin ◽

Juan Deng ◽

Jingping Ouyang

Keyword(s):

Endoplasmic Reticulum ◽

Protein Kinase ◽

Endoplasmic Reticulum Stress ◽

Protective Effect ◽

High Glucose ◽

Hepg2 Cells ◽

Astragalus Polysaccharide ◽

Amp Activated Protein Kinase

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Delphinidin Ameliorates Hepatic Triglyceride Accumulation in Human HepG2 Cells, but Not in Diet-Induced Obese Mice

Nutrients ◽

10.3390/nu10081060 ◽

2018 ◽

Vol 10 (8) ◽

pp. 1060 ◽

Cited By ~ 16

Author(s):

Marcela Parra-Vargas ◽

Ana Sandoval-Rodriguez ◽

Roberto Rodriguez-Echevarria ◽

Jose Dominguez-Rosales ◽

Arturo Santos-Garcia ◽

...

Keyword(s):

Gene Expression ◽

Body Weight ◽

Hepg2 Cells ◽

Molecular Mechanisms ◽

Sirtuin 1 ◽

Standard Diet ◽

Obese Mice ◽

Alcoholic Fatty Liver ◽

Metabolic Alterations ◽

Triglyceride Accumulation

Anthocyanin consumption is linked to benefits in obesity-related metabolic alterations and non-alcoholic fatty liver disease (NAFLD), though the functional role of delphinidin (Dp) is yet to be established. Therefore, this study examined the effects of Dp on metabolic alterations associated with NAFLD, and molecular mechanisms in HepG2 cells and diet-induced obese mice. Cells incubated with palmitate to induce lipid accumulation, concomitantly treated with Dp, reduced triglyceride accumulation by ~53%, and downregulated gene expression of CPT1A, SREBF1, and FASN without modifying AMP-activated protein kinase (AMPK) levels. C57BL/6Nhsd mice were fed a standard diet (control) or a high-fat/high-carbohydrate diet (HFHC) for 16 weeks. Mice in the HFHC group were subdivided and treated with Dp (HFHC-Dp, 15 mg/kg body weight/day) or a vehicle for four weeks. Dp did not affect body weight, energy intake, hyperglycemia, insulin resistance, or histological abnormalities elicited by the HFHC diet. Furthermore, the messenger RNA (mRNA) expressions of Acaca, and Fasn in hepatic or epididymal adipose tissue, and the hepatic sirtuin 1 (SIRT1)/liver kinase B1 (LKB1)/AMPK and proliferator-activated receptor alpha (PPARα) signaling axis did not significantly change due to the HFHC diet or Dp. In summary, Dp effectively reduced triglyceride accumulation in vitro through the modulation of lipid metabolic gene expression. However, a dose of Dp administrated in mice simulating the total daily anthocyanin intake in humans had no effect on either metabolic alterations or histological abnormalities associated with HFHC diets.

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Salvianolic Acid B Attenuates Apoptosis of HUVEC Cells Treated with High Glucose or High Fat via Sirt1 Activation

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2019/9846325 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Jinghui Zhai ◽

Lina Tao ◽

Yueming Zhang ◽

Huan Gao ◽

Xiaoyu Qu ◽

...

Keyword(s):

Oxidative Stress ◽

High Glucose ◽

Molecular Mechanisms ◽

Umbilical Vein ◽

Salvianolic Acid B ◽

Sirtuin 1 ◽

High Fat ◽

Salvianolic Acid ◽

Huvec Cells ◽

Diabetic Cardiopathy

High glucose and high fat are important inducements for the development and progression of diabetic cardiopathy. Salvianolic acid B (SAB), which is the most abundant and bioactive compound in Danshen, attenuates oxidative stress-related disorders, such as cardiovascular diseases, cerebral ischemia, and diabetes. However, the effect of SAB on diabetic cardiopathy is not clear. The aim of study was to investigate the effect and the underlying molecular mechanisms of SAB on diabetic cardiopathy in vitro model. The human umbilical vein endothelial (HUVEC) cells were treated with high glucose (HG, 30 mM) or high fat (palmitic acid, PA, 0.75 mM) in the presence or absence of SAB (100, 200, and 400 mg/L) and incubated for 24 h. We found that HG or PA induced apoptosis of HUVEC cells, while treatment with SAB inhibited the apoptosis. We also found that SAB reversed HG- or PA-induced oxidative stress, apoptosis cell cytokines production, and expression of thioredoxin-interacting protein (TXNIP). Moreover, SAB increased HG- or PA-induced expression of Sirtuin 1 (Sirt1), a nicotinamide adenine dinucleotide- (NAD+-) dependent histone deacetylase. Exposure of HUVEC cells to Ex527 (Sirt1 inhibitor) suppressed the effect of SAB on acetyl-p53 and procaspase-3 expressions. In conclusion, the results suggested that SAB could attenuate HUVEC cells damage treated with HG or PA via Sirt1 and might be a potential therapy agent for the diabetic cardiopathy treatment.

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